/Engine/Source/Runtime/CoreUObject/Public/Misc/AssetRegistryInterface.h
Storage for the singleton IAssetRegistry* TODO: this storage should be a class static variable onIAssetRegistry, but that type is defined in the AssetRegistry module, and many modules try to access the singleton (and call virtual functions on it) without linking against the AssetRegistry module, so the storage for the singleton needs to be defined in a lower-level module that all of those modules do include
class IAssetRegistrySingleton